1. Field of the Invention
The present invention relates to joining two tubes together. The invention specifically relates to joining a small diameter tube to a large diameter tube, such that fluid flow from the small diameter tube may enter the large diameter tube without creating undue turbulence. More specifically, the present invention relates to a pipe joint for use in air conditioning equipment wherein small diameter tubes are joined to large diameter tubes.
2. Description of the Prior Art
In air conditioning and refrigeration equipment it is common to join a small diameter tube such as the capillary tube to a large diameter tube, often a header. The different size tube joints can be found both in the condenser coil and the evaporator coil of a standard refrigeration unit. Another use of a joint between a large diameter tube and a small diameter tube can be found in a heat pump. See Patent Application entitled "Heat Pump System", Ser. No. 720,721, assigned to the assignee hereof wherein a small diameter tube is joined to a large diameter tube to aid in the routing of the refrigerant through the coil depending on whether the coil is used as the evaporator or the condenser of the heat pump.
Prior to the disclosed joint herein it was common to merely form a T-joint wherein the small diameter tube is simply connected to the large diameter tube at right angles. Other types of joints have been utilized wherein the surface of the large diameter tube has been formed outwardly to provide a collar for joining a small diameter tube. Another method of joining small diameter tubes to large diameter tubes is shown in U.S. Pat. No. 2,261,774 entitled "Lubricant Atomizer," wherein the small diameter tube is screwed into the threaded wall of the large diameter tube.
Previous joints have required the use of either the complex screw threads as shown in the U.S. Pat. No. 2,261,774 patent or weak solder arrangements wherein the surfaces of the large and small diameter tubes are joined externally from the large diameter tube. Furthermore the T-joint previously used creates considerable turbulence with the internal flow of the large diameter tube. The fluid flowing through the small diameter tube enters the large diameter tube at right angles creating fluid flow discontinuities. These previous joining efforts further require the drilling of a hole and removal of chips and other machining operations.
The present invention provides for a simple indentation tool to deform a portion of the surface of the tube so that an opening is provided wherein the small diameter tube may be inserted. This opening with the tube in place is then materially joined to form the joint. No screw threads or complicated machining equipment is required. Furthermore the small diameter tube within the opening is directed such that the fluid flow therefrom is parallel to the fluid flow in the large diameter tube.